Saint with total speech difficulty (7)
I believe the answer is:
stutter
'speech difficulty' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'saint with total' is the wordplay.
'saint' becomes 'st' (abbreviation).
'with' means one lot of letters go next to another.
'total' becomes 'utter' (I've seen this before).
'st'+'utter'='STUTTER'
Can you help me to learn more?
(Other definitions for stutter that I've seen before include "Falter" , "Speech impediment" , "Stammer" , "Struggle to speak" , "Speech defect in repeating first consonants of words" .)